Water is generally heated for a spa or the like by a gas fired or electric heating unit and recirculated through the heating unit and the tub of the spa by an electric pump. In most instances the heating unit is separate from the pump, as in Pat. No. 3,630,175 issued Dec. 28, 1981 to Reid, Jr., et at. for FLUID HEATER.
Pat. No. 4,594,500 issued Jun. 10, 1986 to Wright for ELECTRICALLY HEATED PUMP FOR SPAS AND SWIMMING POOLS combines an electric heating unit with a pump as a way to overcome the cost of having separate appliances. Wright combines the heater with the pump, but he still has the cost of installing and the expense of operating a separate heater for the water.